IC chips, such as, MRAM chips, are typically encapsulated in protective packages to prevent errors from stray or externally applied electromagnetic fields and to prevent damage during subsequent processing. MRAM structures, both wire bonded and flip-chip, need to be shielded from all six sides with a protective layer for better protection, however, known wire-bonding shielding approaches result in high package thickness and lower efficiency because (i) the shielding material is not formed in a closed loop, which is especially true for perpendicular MRAM structures; (ii) the wire-bonding pad area is often too big; and (iii) process challenges for wire-bonding if the substrate pad opening area in a printed circuit board (PCB) substrate is too small. Flip chip MRAM packages pose additional problems because (i) flip chip MRAM have a wider bottom shield opening compared to wire-bonding, thereby less magnetic shield efficiency; and (ii) individual openings of the bottom shield promote a high risk of electrical shortage between the metal bumps and shield metal and pose a limitation in terms of fine pitch opening on the bottom shield.
Referring to FIG. 1, a cross-sectional view of a known wire bound MRAM package, protective shield layers 101 and 103 are formed below and over a portion of the MRAM structure 105, respectively, and an epoxy molding compound (EMC) layer 107 is subsequently formed over shield layers 101 and 103, the MRAM structure 105 and the wire 109. As described above, this design is problematic because the protective layers 101 and 103 do not encapsulate the MRAM structure 105 on all six sides. As a result, the MRAM structure 105 is exposed to stray or externally applied electromagnetic fields and to subsequent processing steps. Referring to FIG. 2, a conventional wire bonding package 200 is compared to a known MRAM wire bonding package 202 to show the buildup in MRAM wire-bonding pad area (depicted by the arrow 201) while forming protective layers 203 and 205 over a PCB substrate 207 to protect the MRAM structure 209. Further, the predetermined distance between the MRAM structure 209 and the protective layers 203 and 205 increases the package thickness.
A need therefore exists for methodology enabling magnetically shielding an MRAM structure on all six sides without compromising package thickness.